The low beam headlights are used mostly for city night-time driving, where the glare of high beam headlights might tend to blind or irritate the eyes of a driver in an oncoming vehicle. High beam headlights are used most often in country night-time driving, where there are usually no oncoming vehicles. When an oncoming vehicle is encountered, the driver switches to the low beam headlights.
U.S. Pat. No. 6,206,555, issued to K. Redzinsky, et al on Mar. 27, 2001, refers to a mechanism for adjusting a light source relative to a reflector between a low beam position and a high beam position. The patent disclosure does not show the light source or the reflector, so that the functional effect of the adjusting action is unclear.